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Tufts OpenCourseware
Authors: Kathleen Merrigan, Ph.D., William Lockeretz, Ph.D.


  • Gliessman, S.R. Agroecology: Ecological Processes in Sustainable Agriculture. Chapter 7. Genetic resources in agroecosystems. 1998.
  • Acquaah, G. Principles of Crop Production: Theory, Techniques, and Technology. Chapter 4 (part). Crop improvement. 2002.
  • Crow, J.F. 90 years ago: the beginning of hybrid maize. Genetics. 148:923-928. 1998

Key Questions

Ecological Processes in Sustainable Agriculture

  • What are the sources of phenotypic variation within a species?
  • What are the advantages and disadvantages of monoculture with crops that have been genetically bred for specific traits?
  • Compare traditional plant breeding and genetic engineering.
  • What are the author’s concerns about genetic engineering?
  • What are the advantages and disadvantages of gene banks?

Principles of Crop Production

  • What biological mechanisms existing in plants encourage self and cross pollination?
  • What are some of the common plant breeding objectives in agricultural crop development? What are some of the factors that a plant breeder would focus on in order to achieve these breeding objectives?